HIGH-TEMPERATURE STUDIES OF METALLURGICAL PROCESSES: PART II. THE THERMAL REDUCTION OF CALCINED DOLOMITE WITH SILICON

Abstract

The production of magnesium by the following reaction has been studied:[Formula: see text]The rate of reaction (a) was followed by continuous weight loss measurements of the reactants. Keeping the particle size of the reactants and size and shape of the charge constant, the following factors which affect the yield of magnesium were investigated: (1) temperature, from 1050–1560 °C; (2) pressure, from less than 1 µ to 261 mm of Hg; (3) catalysts, CaF2, BaF2, and MgF2; and (4) ferrosilicon grade, from 18.7% to 96.7% Si.It was found that the yield increased by a factor 1.55 for a 50° increase in temperature over the temperature range investigated. At temperatures below 1300 °C the yield falls linearly with increase in pressure, while at temperatures above 1300 °C the yield remains relatively constant until the pressure exceeds the equilibrium magnesium pressure. All fluoride additions were found to increase the yield, CaF2 being the most effective. The rate of the reaction was also found to have a direct relationship with the silicon activity.